17-epidrospirenone is an epimer of drospirenone, considered to be impurity. Drospirenone is a synthetic progestational compound used as a component of oral contraceptive in combination with ethinyl estradiol.

17-epidrospirenone is a derivative of drospirenone with a reversed configuration of the 17-spirolactone ring had no biological activity. Drospirenone impurity. Drospirenone is a synthetic progestational compound used as a component of oral contraceptive in combination with ethinyl estradiol.

Arenobufagin, a representative natural bufadienolide compound, is the major active component extracted from toad venom. Arenobufagin is a part of Chinese medicine Chan'su. It possesses significant antineoplastic activity in vitro. Antineoplastic activity of arenobufagin was tested using cell lines from different cancers: breast cancer, hepatocellular carcinoma, prostatic cancer, etc. Arenobufagin acts by intercalating with DNA and disrupting the cell cycle. Also it was shown to inhibit PI3K/Akt/mTOR pathway (in hepatocellular carcinoma cells) and inhibit Na, K-ATPase.